Re:Palindrome Detection

[Mephisto]

What the hell is that?  Did you come up with some random code to put on here with some explanation completely off topic from your original question?

Also, just because it runs, does not mean it should be done that way...I'm surprised your compiler would even compile that (unless you're using Microsoft's which doesn't *just* support ANSI standard code; Microsoft likes to have their own standards and things on their own way.  For instance, you could use void main() legally without warnings or errors in MSVC++ or specify scope of variables in your loops, etc.).

[iago]

What the hell is that?  Did you come up with some random code to put on here with some explanation completely off topic from your original question?

Also, just because it runs, does not mean it should be done that way...I'm surprised your compiler would even compile that (unless you're using Microsoft's which doesn't *just* support ANSI standard code; Microsoft likes to have their own standards and things on their own way.  For instance, you could use void main() legally without warnings or errors in MSVC++ or specify scope of variables in your loops, etc.).

There's nothing wrong with loop-scoped variables.

And did you just talk down at Microsoft?

Anyway, let me say it again, talk to your teacher.  You can't do a lot of what you are doing in your code.  

[Zeller]

... or specify scope of variables in your loops ...

Can you give an example or something about that. I dont understand what you mean.

[Tuberload]

... or specify scope of variables in your loops ...

Can you give an example or something about that. I dont understand what you mean.

Code Select Expand


while (true)
{
  int loop_scoped_variable = 1;
}


[Mephisto]

No, I meant you can select that you can declare variables in loops and they will still be in scope outside of the loop.  I believe you can do this in MSVC++, if not, then I'm mistaken...But I'm pretty confident you can.

[MyndFyre]

No, I meant you can select that you can declare loops in variables and they will still be in scope outside of the loop.  I believe you can do this in MSVC++, if not, then I'm mistaken...But I'm pretty confident you can.

You meant that you can declare variables in loops and they will still be in scope outside of the loop.  This is not proper according to C++ 99 (I believe that's the spec) -- variables inside of a loop remain in scope only for that loop.

[Eibro]

No, I meant you can select that you can declare loops in variables and they will still be in scope outside of the loop.  I believe you can do this in MSVC++, if not, then I'm mistaken...But I'm pretty confident you can.

Yes, only VC6 had this problem. It's fixed in VS.net 2002/2003, though there's a compiler option to toggle whether it's enforced or not.
Ex.

Code Select Expand

for ( int i =0; i < 10; ++i ) { /* code.. */ } i = 25 is illegal.

[Mephisto]

Which is exactly what I was pointing out.  And in Eibro's example, you could make his example legal in MSVC++.  This is because Microsoft supports ANSI/ISO C++, but they have their own standards if you want to call it that, and support things that are illegal in C++ standards, such as using void main() function definitions, and variable loop scope resolution.

Thanks MyndFyre, typo.  

[Adron]

Which is exactly what I was pointing out.  And in Eibro's example, you could make his example legal in MSVC++.  This is because Microsoft supports ANSI/ISO C++, but they have their own standards if you want to call it that, and support things that are illegal in C++ standards, such as using void main() function definitions, and variable loop scope resolution.

Thanks MyndFyre, typo.  

You mean, they support things that are different from the latest C++ standards, i.e. they are backwards compatible. Being optionally backwards compatible is a very good thing.

[Mephisto]

Of course.  I don't think I ever said it was a bad thing, I was just pointing out that they support other things in C/C++ that isn't compatable with ANSI/ISO C/C++ standard.

However, if people just learning start out using MSVC++ and tutorials on MSDN and such (which use void main() definitions, and other things that may be illegal in C/C++), the new one starting may develop bad coding.  :p  It should be important to know what the C/C++ standards are and how to properly code in them, and then take advantage of what Microsoft has to offer in their compilers that is illegal in C/C++ standards if you want to...

[AC_Drkan]

Look at my post in Palindrome Detection

[Adron]

Look at my post in Palindrome Detection

Which one? I posted multiple working answers to your problem...

[Banana fanna fo fanna]

Took me a couple minutes and one bug to whip this up. Was a nice little exercise!

Code Select Expand


(define is-palindrome-helper
 (lambda (str start length)
   (if (> start (quotient length 2))
       #t
       (and
        (equal? (string-ref str start)
                (string-ref str (- (- length start) 1)))
        (is-palindrome-helper str (+ start 1) length)
        )
       )
   )
 )

(define is-palindrome
 (lambda (str)
   (is-palindrome-helper
    str
    0
    (string-length str))))

(is-palindrome "racecar")


[dxoigmn]

Took me a couple minutes and one bug to whip this up. Was a nice little exercise!

Code Select Expand


(define is-palindrome-helper
 (lambda (str start length)
   (if (> start (quotient length 2))
       #t
       (and
        (equal? (string-ref str start)
                (string-ref str (- (- length start) 1)))
        (is-palindrome-helper str (+ start 1) length)
        )
       )
   )
 )

(define is-palindrome
 (lambda (str)
   (is-palindrome-helper
    str
    0
    (string-length str))))

(is-palindrome "racecar")


Eww.  What do you use to run that?  Dr Scheme?

[Banana fanna fo fanna]

Yup